HONEYLOCUST RESEARCH NEWSLETTER No.1 March, 1994
TABLE OF CONTENTS
Editorial: Good News …………………………..page 1
Honeylocust AgroforestryScenario page 1
Editor’s Note………………………………………………….page 2
Research Background……………………......page 2
Current Projects………………………………………….page 3
Budding and Grafting Honeylocust…page 4
Further Reading …………………………………... page 5
Many researchers worldwide are now working with various aspects of agroforestry honeylocust: over 30 researchers in eight temperate zone countries. If you are one of these experimenters, take heart and rest assured that you are not alone. The purpose of the Honeylocust Researchers Group(HRG) and this HRG Newsletter is to encourage research with agroforestry honeylocust by facilitating communication among researchers. The newsletter will provide a place to share preliminary findings and pre-publication material, and to obtain answers to questions about on-going work with agroforestry honeylocust.
At present there is insufficient information to recommend commercial adoption of silvopastural honeylocust to livestock raisers. However, during the next decade, the cumulative results of existing experiments should provide an improved guide to honeylocust's commercial value. Present research is concentrated in economically developed countries; ultimately, however, much of this work should have application in temperate regions of developing countries as well. We strongly encourage you to continue with your existing projects. If you are considering beginning a new project or adding to an existing experiment, we urge you to do so.
Research questions to be evaluated include tree-grass interactions, tree protection techniques, pasture and tree fertilization, insect and disease control, pruning regimes, pod yield characteristics of various cultivars, and suitability of pods as self-harvested fodder for sheep. Presently, 42 honeylocust cultivars selected in France, New Zealand, Australia, South Africa, and the United States are being evaluated in pasture trials with animals, and data will be analyzed to determine the cultural and economic feasibility of silvopastural honeylocust. Research questions to be evaluated include tree-grass interactions, tree protection techniques, pasture and tree fertilization, insect and disease control, pruning regimes, pod yield characteristics of various cultivars, and suitability of pods as self-harvested fodder for sheep.
Honeylocust Agroforestry Scenario
While honeylocust (Gleditsia triacanthos L.) have several potential uses in agroforestry, the most promising is as a pasture fodder tree. Honeylocust produce pods which can provide animal feed during autumn and winter when pasture grass production declines. Livestock may harvest the pods directly from under the trees, minimizing harvesting and processing costs. Using tree protectors and/or electric fences, honeylocust orchards can be established in operating pastures and hayfields, permitting cash flows from livestock sales to continue while the trees mature. Pods have a nutritional value between oats and barley, depending on the cultivar, growing conditions, and location. Because sheep can digest the honeylocust seed and require less expensive tree protection, they offer a better fit with silvopastoral honeylocust than cattle or hogs. Economic evaluations of silvopastoral honeylocust indicate internal rates of return of 9% to 25%, depending on a variety of cost and production assumptions. Although not easily quantified, additional benefits include reduction of water runoff and topsoil erosion, shade for livestock, a productive pollen and nectar source for bees, a more diversified and aesthetically pleasing pasture environment, and timber upon project termination.
Despite promising preliminary results, several earlier honeylocust projects in the United States, Algeria, and South Africa were terminated before the trees could mature. For example, in Auburn University trials during the 1940s, average pod yield for 5-10 year old trees were 58kg for the cultivar 'Millwood' and 49kg for 'Calhoun.' The project was discontinued, and the 10-year old trees cut down. As a consequence of the termination of this and other projects, there is now insufficient information to recommend honeylocust for commercial applications. The HRG was organized to encourage those now working with honeylocust to continue with their work; our mailing list has 50 names, most of whom have honeylocust trees.
Each project, large and small, amateur or professional, has an important role to play. Performance data from various locations using a variety of management practices are needed to support the findings from other projects. The cumulative results from present projects will add to the value of individual data. For example, earlier research suggests pod yields and nutritional quality may vary depending on location(between the southern and northern regions of the United States). If you have grafted trees, I urge you to maintain them so pod yield measurements can be made. If you have seedling trees, grafting them to existing cultivars is important to permit meaningful comparisons. More information is also needed on project details and management practices: tree establishment and protection, grafting methods, tree spacing, and control of insects and disease problems.
As long ago as the 18th century, the honeylocust was recognized as a fodder tree with high potential. Formal research with agroforestry honeylocust began in South Africa(1908), the United States(1938), Algeria(1956), and New Zealand(1958). In the United States, the government-financed Tennessee Valley Authority planted honeylocust orchards at Auburn(Alabama), Tennessee, and Virginia Tech Universities. Unfortunately, these orchards were abandoned after World War II as agricultural research priorities shifted to monoculture crop systems. In 1990 I located the remnants of the orchard at Virginia Tech. Thirty-four out of the original 160 grafted 'Millwood' cultivar trees remained. This orchard of 50-year old trees occupied by grazing animals was an inspiring sight. The trees, spaced too closely at 20 feet by 30 feet, had not been maintained and were not in good shape. Nevertheless, animals had been grazing under the trees, and the orchard suggests unexploited potential of silvopastoral honeylocust.
With a couple of notable exceptions, research with honeylocust remained dormant until the 1980s. In the early 1980s, Greg Williams, then with International Tree Crops Institute in Kentucky, distributed honeylocust seed, scionwood, and grafted trees to over 100 organizations and amateur researchers worldwide. In 1990 I contacted these researchers, and although only 20 reported extant trees, this group became the core of the Honeylocust Research Group.
In 1980, Professor Michael Gold, then a doctoral student at Michigan State University, organized a major germ plasm collection, and with this material established a range-wide provenance, half-sib progeny planting containing 250 sources at two Michigan locations. Maintenance and monitoring of these sites continue. Trees have begun fruiting, and when selections are made, these trees should offer a rich source of improved cultivars.
In 1982, largely as the result of the oil crises of the 1970s, the TVA again obtained funding, this time to test the efficiency of honeylocust pods as an ethanol fuel source. They financed the planting of five honeylocust orchards averaging 100 trees each. But after oil prices dropped, funding was again discontinued, and only two of these orchards, one operated by Hector Black at Hidden Springs Nursery in Tennessee, and the other by Ken Ladd, in Jasper, Arkansas, are still in existence.
In 1982, I began a pasture honeylocust demonstration project at the communally-operated Springtree farm in central Virginia. Grafted trees were planted in operating pastures and protected by electric fences and later plastic tree shelters. Now over 70 trees, this planting forms the basis for the Springtree Agroforestry Project.
In the search for honeylocust researchers, my biggest surprise and delight were the extent and depth of on-going work outside the United States. Through a variety of sources and contacts(many thanks to those helpful individuals), I have located honeylocust projects in eight temperate zone countries. Although honeylocust is native to most of the Mississippi Valley in the eastern United States, it has adapted well to the temperate zone worldwide, first as an urban shade tree and more recently as a possible agroforestry species.
In 1991 I visited premier agroforester Christian Dupraz in Montpellier, France. Christian has selected 12 honeylocust seedlings found in France and established a 196-tree honeylocust orchard to evaluate these cultivars. Selecting the four best cultivars, he has established two experimental orchards in cooperation with sheep farmers near Montpelier, and facilitated the establishment of two more orchards in Greece. In addition, Christian has coordinated extensive experiments feeding honeylocust pods to sheep. Results of these experiments have been most encouraging, with sheep showing substantial weight gains.
The Future: I plan to publish the HRG Newsletter annually. Next year's newsletter will include information on honeylocust cultivars for agroforestry and their availability, an up-date on various grafting techniques, methods for measuring pod yields, and descriptions of existing research projects. If you have honeylocust scionwood for exchange or sale, please let me know. Comments and suggestions are welcome, and I will try to find answers to your questions related to agroforestry honeylocust. So please send a note on how your project is going, your important results to date, and what problems you have encountered.
Budding and grafting honeylocust. Budding honeylocust in the spring using dormant scionwood gives generally poor results. To produce honeylocust shade trees, United States commercial nurseries bud in May/June using scionwood taken from this year's growth. Rootstock to be budded is often cut to the ground before bud break to produce a more succulent budding area. It is not too late to add to your honeylocust planting this year. Seedlings can be purchased from commercial nurseries and additional scionwood can be cut from your trees, or a limited supply can be obtained from Springtree Agroforestry Project. H.G.Hallum Nursery (122 Hallum Lane, Minnville, TN 37110) has seedlings from a southern seed source. If you have established seedlings that have grown too large to bud, I recommend a standard bark graph with dormant scionwood. The bark graft is not pretty but it works well(80 percent takes). I have prepared an information sheet on budding and grafting honeylocust which is available on request.
Grafted Honeylocust Available. I have received many requests from individuals wishing to purchase budded honeylocust. Hector Black, Hidden Springs Nursery will have budded honeylocust available in the spring of 1996. The selection of tree crop species at Hidden Springs Nursery is one of the very best.
Suggested management practices
Management practices for silvopastoral honeylocust should be focused on developing rapid growth in young trees, leading to early and heavy pod production.
1. Maintain soil pH between 6.5 and 7.5, and at least at 6.0.
2. Use tree shelters and/or other devices to protect trees from rodents, deer, and livestock. Honeylocust's thin bark makes it particularly susceptible to animal browsing and rubbing damage.
3. Stimulate early tree growth by providing adequate water and fertilizer. Suppress competitive grasses and weeds around the tree.
4. Monitor trees for insect and disease problems, and take appropriate control measures. Use Bacillus thuringienis to control mimosa webworm.
5. Prune young trees to a central leader.
Further reading. The following sources are recommended for additional information on agroforestry honeylocust.
Gold, M.A. and Hanover, J. W. 1993. Honeylocust(Gleditsia tricanthos L.), Multipurpose tree for the temperate zone. International Tree Crops Journal. In Press.
Scanlon, D.H. 1980. A Case Study of Honeylocust in the Tennessee Valley Region. In Tree Crops for Energy Co‑Production on Farms. U.S. Solar Energy Research Institute. Golden, Colorado.
Wilson, A.A. 1993. Silvopastoral agroforestry using honeylocust (Gleditsia triacanthos L.) Proceedings of the Third North American Agroforestry Conference. Iowa State U. Ames, Iowa. In Press. Copies available from Springtree Agroforestry Project.
The bibliographies in these sources provide additional information on agroforestry honeylocust.
Information on Temperate Zone Agroforestry
For information on temperate zone agroforestry in general, I recommend the proceedings of the three biennial North American Conferences on Agroforestry, and the newsletter of the Association for Temperate Agroforestry(annual membership is US$15 for individuals; write Dr. Michael Gold, Department of Forestry, Michigan State University, East Lansing, Michigan 48824 USA).
Williams, P.(ed.) 1991 Agroforestry in North America: Proceedings of the First Conference on Agroforestry in North America. U. of Guelph, Guelph, Ontario, Canada. (Conference held in 1989)
Garrett, H.E.(ed.) 1991. The 2nd Conference on Agroforestry in North American. U. of Missouri, Columbia, Missouri.
Schultz, R.C. and J. Colletti(eds.) 1994. Third North American Agroforestry Conference. Iowa State U. Ames, Iowa. In Press.
For those interested in an electronic connection, there is a USENET newsgroup called bionet.agroforestry which can be accessed via the Internet.
For pure inspiration, read J. Russell Smith's Tree Crops: a permanent agriculture. Devin-Adair, New York, NY. Second edition, 1950. This is the classic work on temperate zone agroforestry.Honeylocust pioneer Ralph Kreider in Hammond, Illinois, who in 1949 planted and has maintained over 100 Millwood seedlings, re-read Smith's Tree Crops each winter for 15 years.
HRG NEWS is written by Andy Wilson and produced by the Springtree Agroforestry Project(Ruth Klippstein, Evelyn Edson, Tom Klippstein, and Andy Wilson), 268 Springtree Lane, Scottsville, VA 24590 USA. Phone: 434-286-3466, Fax: 434-286-3771.